| 摘要 |
Charged-particle-beam (CPB) optical systems (especially projection-lens systems for use in CPB microlithography apparatus) are disclosed that exhibit excellent control of geometric aberration and the Coulomb effect while exhibiting low combined aberration and blur. As the column length of the projection-lens system is increased, geometric aberration is reduced but the Coulomb effect increases, which degrades overall optical characteristics. Conversely, as the column length is decreased, the Coulomb effect is reduced but geometric aberration increases, which degrades overall optical characteristics. Hence, the projection-lens system, exhibiting a magnification of 1/M and having a column length (distance in mm between reticle and wafer) of 250xM<0.63>±10% (wherein 0<M; e.g., 0<M<4 or 4<M) exhibits blur and geometric distortion of about 70 nm or less and about 4 nm or less, respectively.
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